jquery radiobutton select change

                <asp:RadioButtonList ID="rbtResourceType" runat="server" class="radioItem" RepeatLayout="Flow" RepeatDirection="Horizontal" >

                        <asp:ListItem>代理招生</asp:ListItem>

                        <asp:ListItem>市场活动</asp:ListItem>

                        <asp:ListItem>老师推荐</asp:ListItem>

                        <asp:ListItem>学员推荐</asp:ListItem>

                        <asp:ListItem>其他</asp:ListItem>

               </asp:RadioButtonList>

        <script type="text/javascript">

            $(document).ready(function () {

                $(".radioItem").change(function () {                            

                    var selectedvalue = $("input[name='rbtResourceType']:checked").val();

                    alert(selectedvalue);

                });

            });
        </script>